可加工玻璃陶瓷液相法制备工艺及其性能研究

发布时间：2018-01-23 14:02

  本文关键词： 液相沉淀法 玻璃陶瓷 形核 晶化 烧结行为 可加工性　出处：《西安工业大学》2010年硕士论文　论文类型：学位论文

【摘要】： 目前陶瓷材料作为一种新型的工程结构材料,在宇航、汽车、冶金、化工、机械等领域得到了越来越广泛的应用。可加工玻璃陶瓷材料以其优异的美观性能、可切削性能和机械力学性能等正日益受到人们的重视。但是目前国内外常用的制备玻璃陶瓷的方法主要有熔融法、烧结法和溶胶-凝胶法,前两种的制备方法复杂,制备出的晶粒尺寸粗大,且消耗电能,而溶胶凝胶法成本偏高,不适合工业生产的要求,因此玻璃陶瓷材料的制备工艺仍然是研究的重点。 本文在玻璃陶瓷的制备方法上做了改进,根据低温液相均匀沉淀法的机理,制备了纳米级的钠氟金云母(NaMg3AlSi301oF2)玻璃陶瓷前驱粉体,并对前驱粉体进行晶化热处理,得到主晶相为钠氟金云母的玻璃陶瓷的粉体,经成型和烧结后得到云母基玻璃陶瓷。采用DTA/TGA、TEM、XRD、FT-IR、SEM和ESCA等手段,研究了材料的制备工艺和制备过程中的物相变化,微观形貌和结构的演变,探讨了陶瓷成分和结构对其各项性能的影响,并对钠氟金云母玻璃陶瓷的可加工性能做了检测。实验获得的主要成果如下： 选取了几种分别含有Na+、Mg2+、Al3+、Si4+、F-的水溶性化合物作为液相反应的原材料,通过控制工艺参数,制备出了分散性良好、大小均匀的纳米级前驱粉体,一次粉体粒径在10-20nm之间,二次颗粒大小约为100nm,颗粒呈近球状,为典型的非晶态硅酸盐粉体。 对前驱粉体晶化热处理发现,钠氟金云母晶核结构主要在600℃左右开始出现,650℃左右形核速率最大,从700℃左右开始形核速率减至最小,晶化温度为950℃时,钠氟金云母晶核生长速度较大,晶化过程中伴随着镁橄榄石(Mg2Si04)和霞石(NaAlSi04)析出。粉体最佳的热处理制度是650℃核化2h,950℃晶化0.5h,热处理后粉体主要呈现层片状钠氟金云母晶相形貌,晶化度达到45%左右。实验发现核化温度对粉体的析晶行为影响最大,然后是晶化温度,最后是保温时间的影响。 粉体成型采用阶梯式单向加压方式,先在大约40MPa的压力下保压1min,然后再加压到100MPa,保压2min。烧结工艺为550℃保温2h,升温到1120℃保温2h。 研究发现,烧结后玻璃陶瓷内部主晶相为层片状的钠氟金云母晶相,径长约为10μm,晶化程度达到52%,相对密度达到96.8%。钠氟金云母晶体含量在烧结过程中随温度的升高先增大后减少,烧结温度过低或过高,均会出现小颗粒状的镁橄榄石和短柱状的霞石,这两种晶相的变化趋势大致与钠氟金云母晶体的变化相反。 综合各项性能发现,显微结构对玻璃陶瓷的性能有很显著的影响,三点弯曲强度值随着烧结温度先升高后降低。钠氟金云母玻璃陶瓷合适的烧结温度为1120℃,此时玻璃陶瓷的晶化程度最高,片层状云母晶体的长厚比大,相互交错的程度高,三点弯曲强度达到了116.76MPa,硬度为3.23GPa,实验证实材料具有较好的可加工性能。
[Abstract]:At present, ceramic materials as a new type of engineering structural materials, in aerospace, automotive, metallurgy, chemical, mechanical and other fields have been more and more widely used. Machinable glass ceramic materials for its excellent aesthetic properties. People pay more and more attention to the machinability and mechanical properties of glass ceramics. However, the main methods used to prepare glass ceramics are melting, sintering and sol-gel methods. The former two preparation methods are complex, the grain size is coarse, and the electric energy is consumed, but the cost of sol-gel method is high, which is not suitable for industrial production. Therefore, the preparation of glass ceramic materials is still the focus of research. In this paper, the preparation method of glass ceramics has been improved, according to the mechanism of low temperature liquid phase homogeneous precipitation method. Nano-sized NaMg3AlSi301oF2 glass ceramic precursor powder was prepared, and the precursor powder was crystallized by heat treatment. The main crystalline phase of the glass ceramic powder is sodium fluorophlogopite. After forming and sintering, the mica based glass ceramics are obtained by using DTA / TGA TGA TGA TGM XRDX FT-IR. By means of SEM and ESCA, the preparation process and the changes of phase, microstructure and microstructure of the materials were studied, and the effects of ceramic composition and structure on their properties were discussed. The machinability of sodium fluorophlogopite glass ceramics is tested. The main results are as follows: Several water-soluble compounds containing Na ~ (2 +) mg _ (2) O _ (3) Al _ (3) O _ (3) Si _ (4) F _ (-) were selected as raw materials for liquid phase reaction. By controlling the process parameters, good dispersity was obtained. The size of nanometer precursor powder is uniform, the primary particle size is 10-20 nm, the secondary particle size is about 100 nm, the particle is nearly spherical, and it is a typical amorphous silicate powder. The crystallization heat treatment of precursor powder shows that the nucleation rate of sodium fluorophlogopite begins to appear at about 600 鈩，

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